In recent years and, especially since the advent of plastic pipes, such as polyethylene (PE), polyvinyl cloride (PVC), polybutylene (PB), and the like, for use in fluid distribution systems, such as water or gas, there has been considerable research in developing "stab" type fittings for coupling plastic pipe to metal pipe or to other plastic pipe. While other types of couplings for plastic pipe have been designed, these usually required a solvent weld or a heat weld or flaring the end of the plastic pipe when inserted through a ring nut used to make up a joint and these prior practices required considerable skill and time to complete the coupling joint and in many cases where inexperienced personnel were performing the operation, leaks or improper joints resulted and the pipes were damaged.
The stab type of coupling jont for flareless or smooth end plastic pipe have proved quite successful in that they have reduced the cost and labor savings as well as providing an ease of proper installation even by inexperienced personnel. However, there have been some problems in installation of stab type joints between a fitting or another pipe and a smooth end pipe, or for that matter, a smooth end metallic pipe, in that the installer sometimes did not stab the pipe into the fitting a sufficient distance and further with the improvements in the gripping means of the fitting or in instances where the pipes and fittings were of extremely large size, it was often difficult and sometimes impossible to manually stab the pipe axially into the fitting.
Typical examples of stab type coupling joints for plastic pipe may be found in U.S. Pat. No. 3,815,940, issued June 14, 1974 to LUCKINBILL, U.S. patent application Ser. No. 504,249, filed Sept. 9, 1974 by LEOPOLD ET AL. and U.S. patent application Ser. No. 512,484, filed Oct. 4, 1974 by ELLIS, all being assigned to the same assignee as this application, namely, MUELLER CO., Decatur, Illinois. An additional example of such a coupling joint may be found in U.S. Pat. No. 3,844,585, issued Oct. 29, 1974 to SANDS ET AL. and assigned to MUELLER CO., the coupling joint being shown in FIGS. 7-9 and including an activating plug having a disc therein and a cutter which is activated upon completion of the joint by the stabbing of the pipe, the cutter severing at least a portion of the disc to provide communication with a pipe already under fluid pressure.
In order to improve the make up of a stab type coupling joint, mechanical means such as pliers and other tools have been developed and used. Where special tools were used, these usually included a tool having a first gripping means for gripping the fitting and a second gripping means for gripping the pipe and a complicated linkage and handle system connecting the two for moving the two towards and away from one another so that the pipe and the fitting moved relative one another in a generally axial direction. Usually these tools were quite complicated and expensive to manufacture and could be used only on one size of fitting of pipe. While most of these tools were primarily designed for assembling bell and spigot joints, there have been other tools of this character designed for smaller fittings and pipes but they have not been particularly designed for the utility of use with different size pipes and the gripping means for the tools were not designed for protecting the plastic pipe from damage by permanently marking the pipe with scratches on the exterior surface or from deforming the pipe in an out of round shape during installation which would cause possible improper installation. Additionally, such prior art tools did not accurately control the amount of movement of the respective gripping means of the tool relative one another and in most instances they involved complicated leverage systems which made the tool costly and bulky in size and yet they still required considerable manual effort upon the operator to complete a joint.